Most research concerning clients of commercial sex workers (CSWs) relies upon CSW reports of client characteristics and behavior. We describe correlates of ever purchasing sex among 3,829 men from three cities: São Paulo, Brazil; Cuernavaca, Mexico; and Tampa, USA. A computer-assisted self-interview collected data on demographics and sexual behavior. There were significant site differences—26.5 % paid for sex in São Paulo, 10.4 % in Cuernavaca, and 4.9 % in Tampa. In all cities, men who had sex with men and women (versus sex with women only) were more likely to have ever paid for sex. In São Paulo and Cuernavaca, CSW clients were older, had higher educational attainment, and were less likely to be married. In Tampa, older age was associated with being a CSW client but not education and marital status. In São Paulo and Cuernavaca, CSW clients had more partners than men who had never paid for sex. In São Paulo, CSW clients initiated vaginal sex at an earlier age, while in Cuernavaca they were more likely to self-report a sexually transmitted infection. CSW clients varied with respect to demographics across the three cities while the association between paying for sex and risky sexual behavior seems to be somewhat conserved. These findings suggest that interventions among CSW clients should focus on condom use with commercial and non-commercial partners as these men may be at increased risk for transmitting and acquiring sexually transmitted infections to and from their sex partners. Better understanding of client characteristics is needed for targeting interventions and creating culturally appropriate content.